Dec. 28 (Bloomberg) -- The uphill climb for Democrats to
defend their 53-47 Senate majority next year just got steeper
with the decision by Nebraska’s Ben Nelson not to seek re-election.

Nelson, 70, became the seventh member of the Senate
Democratic caucus to announce his retirement, saying in a
videotaped statement yesterday that “it’s time to move on.”

Democrats are defending 23 seats in 2012, compared with 10
for the Republicans. Nelson’s retirement gives Republicans an
edge in Nebraska, where he is the only Democrat currently
elected to statewide office, and in their campaign to take over
the Senate, political analysts say.

“It qualitatively changes things for Democrats” because
‘I don’t see a path to victory for Democrats in Nebraska,” said
Jennifer Duffy, a Senate analyst for the non-partisan Cook
Political Report. Nelson’s retirement next year “puts
Republicans one seat closer to a majority.”

To wrest control of the Senate, Republicans need a net gain
of four seats in next November’s elections if President Barack
Obama wins a second term. A Republican victory in the
presidential race would reduce the needed pickup to three seats
because the vice president casts tie-breaking votes.

‘Significant Blow’

The retirements of both Nelson and fellow prairie Democrat
Kent Conrad of North Dakota dealt “a significant blow to
Democrats’ chances of holding the Senate,” said Nathan
Gonzales, political editor of the nonpartisan Rothenberg
Political Report.

Democrats are “defending eight out of the 10 most
competitive seats in the country,” Gonzales said in an
interview. Other competitive races include freshman Democratic
Senator Jon Tester’s bid for re-election in Montana, where he is
being challenged by Republican Representative Denny Rehberg.

By contrast, the “two most vulnerable Republicans” are
Senator Scott Brown in Massachusetts and Dean Heller in Nevada,
Gonzales said. Both of their races are tossups as well, he said.

In Nebraska, Nelson, a former two-term governor and state
insurance commissioner, was the Democrat best able to defend the
Senate seat for his party, Duffy said.

If Nelson had stayed in the race, Republicans “were going
to have to fight” to defeat him, she said in a telephone
interview. Now, she said, “there is no obvious Democratic
replacement to Nelson.”

‘Cornhusker Kickback’

Not always a reliable vote for Democrats, Nelson secured a
concession for Nebraska in return for supporting President
Barack Obama’s health-care legislation over a crucial procedural
hurdle in 2009. Republicans derided the provision exempting
Nebraska from paying for expanded Medicaid coverage as the
“Cornhusker Kickback.” Nelson later asked that all states be
treated equally.

A recent Republican political ad accused Nelson of
accepting a bribe for his vote for the health-care legislation.

A maverick in his caucus, Nelson voted against legislation
in August to raise the nation’s debt ceiling, saying it “sets
up a maze of convoluted procedures that will only continue the
chaos and political games Nebraskans are tired of seeing.”

In 2005, when Republicans ran the Senate, Nelson was part
of the bipartisan “Gang of 14” senators who agreed not to
block judicial nominations except under “extraordinary
circumstances.” The agreement averted a threat of legislative
gridlock in the Senate over confirmation of President George W.
Bush’s appointments to the federal bench.

‘Overlooked’ Trait

Senator Patty Murray of Washington state, chairwoman of the
Democratic Senatorial Campaign Committee, played down the impact
of Nelson’s retirement on next year’s election.

“We remain confident that we will hold the majority next
year because incumbents have built strong campaign organizations
in their states,” Murray said in a statement. “Republicans
will continue to have their hands full with a very divisive
primary” in Nebraska, “which will provide an opportunity for
Democrats to remain competitive.”

For its part, the National Republican Senatorial Committee
said in a statement that Nelson’s support for Obama’s agenda
“left him in a grave political situation” even after his party
“poured roughly $1.5 million dollars into Nebraska in the off-year, at the expense of other vulnerable seats.”

Three Republicans

So far, three Republicans, state Attorney General Jon
Bruning, state Treasurer Don Stenberg and Deb Fischer, a state
senator, are seeking the Republican nomination for Nelson’s
seat.

Dave Heineman, Nebraska’s Republican governor, told
reporters earlier this month that he had rebuffed overtures by
party officials in Washington, including Senate Minority Leader
Mitch McConnell of Kentucky, about running for the seat.

“I understand their arguments,” Heineman was quoted as
saying by the Omaha World-Herald. “They’re persuasive. But I
also indicated that it would take a lot to change my mind.”

Possible Democratic candidates identified by the newspaper
include former Lieutenant Governor Kim Robak and Steve Lathrop,
a state senator.

Bob Kerrey, a former Democratic senator from Nebraska, had
also been mentioned on political blogs as a possible candidate
if Nelson retired. Kerrey, who recently retired as president of
the New School in New York, told Nebraska.Watchdog.org on Dec. 9
that running for the Senate is “not what I would consider being
my logical career path.”

Duffy said that while the former senator, who held the seat
from 1989 to 2001, “in theory” is “a really good candidate,
in practice, I think it would be tough” because “it’s been a
really long time since Bob Kerrey has been on the ballot.”

‘Tough Road’

“It’s a pretty tough road” for Democrats in Nebraska,
“where Obama is so unpopular,” she said.

Among the Republicans, two senators -- Kay Bailey Hutchison
of Texas and Jon Kyl of Arizona -- are retiring. A third, former
Nevada Senator John Ensign, resigned during an ethics inquiry,
and Heller, his appointed successor, is now running for a full
six-year term.

Nevada is an opportunity for Democrats because it’s “a
swing state” where “the presidential race is going to have an
impact over the outcome,” Duffy said.

Democrats “could dramatically help themselves” by
defeating both Brown in Massachusetts and Heller in Nevada,
Rothenberg’s Gonzales said, adding: “It’s certainly possible
but it’s not going to be easy.”

Warren’s Challenge

Brown is being challenged by an electoral novice, Elizabeth
Warren, a Harvard Law School professor whom Obama tried
unsuccessfully to install as head of the new Consumer Financial
Protection Bureau.

While Obama is expected to easily carry Massachusetts,
Warren “hasn’t been in the race long enough to give her a final
grade on candidate skills,” Gonzales said.

“She has high approval ratings in Las Vegas, but how wide
is her appeal outside of Vegas? We don’t know yet,” Gonzales
said.

Virginia Contest

Another state where presidential politics could affect the
outcome is Virginia, Duffy said. There, two former governors,
Democrat Tim Kaine and Republican George Allen, are vying for
the seat being vacated by Democrat Jim Webb, who is retiring.
Webb’s defeat of Allen in 2006 helped hand Democrats control of
the Senate.

The other retiring Democratic senators are Daniel Akaka of
Hawaii, Herb Kohl of Wisconsin and Jeff Bingaman of New Mexico.
Connecticut independent Joseph Lieberman, who caucuses with the
Democrats, also isn’t seeking re-election.

In Hawaii, “Republicans found and got the one candidate to
make it a race” -- former governor Linda Lingle, Duffy said.